Add gfycat support

[ScreamingHawk]

Depends on #13

e.g.
https://gfycat.com/teemingashamedhydatidtapeworm-rise-and-shine-good-morning-wake-up

[ScreamingHawk]

Note: Requires capitalization of the URL.

Better to use the API https://developers.gfycat.com/api/#getting-gfycats